Justin D.
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 Dec4 awarded Notable Question Dec2 awarded Popular Question Nov22 awarded Popular Question Sep24 awarded Popular Question Jul2 awarded Curious Apr15 awarded Popular Question Jan29 revised taylor series for cosx around 0 LAtex formatting Jan29 suggested approved edit on taylor series for cosx around 0 Jan28 comment Proof that $AI_n = A$ using $Ab_i$. Thanks for the clarification! I had a hard time visualizing the matrices but you made it very clear. Thanks again. Jan28 accepted Proof that $AI_n = A$ using $Ab_i$. Jan27 comment Proof that $AI_n = A$ using $Ab_i$. OK so if I understand well, $I_n = [b_1 b_2 b_3 \dots b_n]$ where each $b_i$ is a column vector. When you say $A(b_1\dots b_n)$, is $(b_1\dots b_n)$ a matrix or $b_1 \cdot b_2 \cdot \dots \cdot b_n$? Jan27 comment Proof that $AI_n = A$ using $Ab_i$. @ChristopherErnst, how is $I_n = (b_1\dots b_n)$? Is the definition using matrix multiplication? Jan27 asked Proof that $AI_n = A$ using $Ab_i$. Nov19 accepted Monotonic uniformly continuous function - Unique $f(t) = t$ Nov18 comment Monotonic uniformly continuous function - Unique $f(t) = t$ OK, I understand your hint now. (it seems I was not in the right track... thanks!) Nov18 comment Monotonic uniformly continuous function - Unique $f(t) = t$ @BettyMock, I am actually using Bolzano's Intermediate Value Theorem which I think does not require the endpoints to be of different signs Nov18 comment Monotonic uniformly continuous function - Unique $f(t) = t$ @StephenMontgomery-Smith, I don't understand your hint. You want me to feed them into $|f(x)-f(x')| < |x-x'|$? Is the goal to show monotonicity or $f(t)=t$? Nov18 asked Monotonic uniformly continuous function - Unique $f(t) = t$ Nov5 accepted Example to $\lim f(x)g(x)$ may not exist Nov5 comment Example to $\lim f(x)g(x)$ may not exist That's actually what I had at first (with 1 instead of 5). If I take $g=1$, does $fg = f$ (even if $f$ is defined by part)